Key fob battery

[Dogfuzz]

Are there symptoms of a key fob battery that needs changing other than complete failure to open doors when pressed.?

Is fob battery a service item? If not-why not?

Mine went a month ago then sure enough 3 weeks later my wife’s went. I shall change both my keys together next time…and do it once a year too so as to avoid the annoying and alarming experience of complete and utter vehicle immobility

[Percy247]

Most dealerships are too lazy to change these. Duracell CR2032 batteries cost less than a £1. I change them annually on all our cars and it takes no more than a minute or two.

[st3v3cx-3]

I've had Mazda dealers recommend when my car was in for a service that the key fob battery is low and needs replacing. They said they'd replace it for £20 or £15 charge! I declined and did it myself. Would have thought for the cost of an annual service it could include a free battery replacement.

Regarding the type of battery, the owner's manual does say a CR2025 or equivalent - see attached

Mazda CX-3 Key fob battery replacement.pdf

(65.01 KiB) Downloaded 401 times

I never did realise what the CR2025 and CR2032 naming meant till I searched today. It seems the 20 bit refers to the mm diameter of the cell, whereas 25 and 32 refer to the mm thickness. Also apparently the CR2025 generally is 165mAh whereas the CR2032 is a higher 225mAh. Might mean the CR2032 will last longer? I'm sure I've used both when doing my replacements - each fitted and worked without any problem.

[Dogfuzz]

My model uses the 2025. The 2032 is too thick.
There is a mini you tube video showing you how to do it. Just key in "Change battery of key fob-Mazda CX 3". Jobby took less than 2 mins.
Thanks everyone.
Why on earth did a dealer threaten to charge £20 to do this?

[Percy247]

I guess dealers are offering a service for that 1 person in 50 who can't change a key fob battery or wiper blade or doesn't know someone who can. The days of doing something for nothing or for just the cost of the part are long gone!

[st3v3cx-3]

The cost of a new key fob battery and fitting it when a car is booked in for an annual service could easily be buried in the usual miscellaneous consumables add-on and by adding 0.1 labour hours to the book time for carrying out the service.

[Kimm]

My key fobs started failing very suddenly. I had the original battery last about 4 years and now I seem to be replacing them every 6-12 months. I started carrying replacements around with me because twice now I had the battery just completely die. Not sure if it’s a coincidence or not but only started having trouble when I started using a faraday bag to keep them in.

[AndyRen]

Not sure if it’s a coincidence or not but only started having trouble when I started using a faraday bag to keep them in.

We use Faraday bags and have not noticed any fob battery problems. IIRC 12 months is recommended for battery replacement?

With my VR6 I noticed the fob battery would fail very quickly.... Then I realised I was tapping out the beat on one of the fob buttons to whatever music I had drifting around in my head whilst out walking! Aint life weird?!

BTW, I would check your Faraday cage case/bag whatever, every few months or so, the folding flap on one of ours wore out rendering it useless - and that was a Defender bag.

[Kimm]

Not sure if it’s a coincidence or not but only started having trouble when I started using a faraday bag to keep them in.

We use Faraday bags and have not noticed any fob battery problems. IIRC 12 months is recommended for battery replacement?

With my VR6 I noticed the fob battery would fail very quickly.... Then I realised I was tapping out the beat on one of the fob buttons to whatever music I had drifting around in my head whilst out walking! Aint life weird?!

BTW, I would check your Faraday cage case/bag whatever, every few months or so, the folding flap on one of ours wore out rendering it useless - and that was a Defender bag.

Yes thanks I replaced the bag a few months ago as once the Velcro is knackered it no longer works, I check them periodically to check they are doing the job still. Seems that the button on my fob could well be being pressed in my bag amongst the clutter therefore wearing it out quicker than it should be worn out.

[TEB]

Dealer changed both our keys batteries as they thought they could be part of the issues I was having with the mirrors and locks, think they billed us around £7.

Only other car I've ever found need to change the key battery was a Panda 4x4 which gave up the ghost after 2 years.